A method and apparatus for encoding an image is provided. The method and apparatus include quantizing and entropy encoding a second frequency coefficient matrix that is generated by performing a partial exchange of one or more values between rows and between columns of a first frequency coefficient matrix. A method and apparatus for decoding image data that is encoded by using the method and apparatus for encoding the image is also provided.
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1. A method of encoding an image, the method comprising: generating a first frequency coefficient matrix; generating a second frequency coefficient matrix by performing a partial exchange of one or more values between at least two rows or between at least two columns of the first frequency coefficient matrix based on an angle parameter; quantizing the second frequency coefficient matrix; and entropy-encoding the second frequency coefficient matrix and information regarding the angle parameter, wherein the angle parameter is a parameter that indicates a level of the partial exchange of the one or more values between the at least two rows or between the at least two columns of the first frequency coefficient matrix.
A method for encoding an image involves several steps. First, a "first frequency coefficient matrix" is generated, likely representing frequency components of the image (e.g., from a DCT transform). Then, a "second frequency coefficient matrix" is created by partially exchanging values between rows or columns of the first matrix. The extent of this exchange is determined by an "angle parameter." This second matrix is then quantized and entropy-encoded, along with information about the "angle parameter" used for the exchange. The "angle parameter" determines how much the values are swapped.
2. The method of claim 1 , wherein the angle parameter is a parameter with respect to an Euler angle.
The image encoding method described previously where a "second frequency coefficient matrix" is created by partially exchanging values between rows or columns of the first matrix based on an angle parameter, specifies that the "angle parameter" used to control the exchange of values is based on Euler angles. Euler angles can represent rotations in 3D space, therefore, the exchange of values in the frequency coefficient matrix is determined by one or more Euler angles.
3. The method of claim 1 , wherein the generating of the second frequency coefficient matrix comprises multiplying a matrix for performing the partial exchange between the at least two rows of the first frequency coefficient matrix by a left side of the first frequency coefficient matrix, and multiplying a matrix for performing the partial exchange between the at least two columns of the first frequency coefficient matrix by a right side of the first frequency coefficient matrix.
The image encoding method where a "second frequency coefficient matrix" is created by partially exchanging values between rows or columns of the first matrix based on an angle parameter, includes a specific way to perform the partial exchange. It multiplies the "first frequency coefficient matrix" by other matrices. A matrix for row exchange is multiplied on the left side of the first matrix, and a matrix for column exchange is multiplied on the right side of the first matrix. This combines row and column exchanges into a single operation.
4. The method of claim 3 , wherein the matrix for performing the partial exchange between the at least two rows or the at least two columns of the first frequency coefficient matrix is ( A B C 0 D E F 0 G H I 0 0 0 0 1 ) , wherein A=cos α cos γ −sin α cos β sin γ , B=−sin α cos γ −cos α cos β sin γ , C=sin β sin γ , D=cos α sin γ +sin α cos β cos γ , E=−sin α sin γ +cos α cos β cos γ , F=−sin β cos γ , G=sin α sin β , H=cos α sin β , I=cos β , and wherein the α, β, γ are Euler angles.
The image encoding method where a "second frequency coefficient matrix" is created by partially exchanging values between rows or columns of the first matrix based on an angle parameter, and the exchange is performed by multiplying matrices on the left and right of the first frequency coefficient matrix, specifies the matrix used for the partial exchange. That matrix is defined as (A B C 0 D E F 0 G H I 0 0 0 0 1), with A, B, C, D, E, F, G, H, and I being trigonometric functions of Euler angles α, β, and γ (A=cos α cos γ −sin α cos β sin γ, B=−sin α cos γ −cos α cos β sin γ, C=sin β sin γ, D=cos α sin γ +sin α cos β cos γ, E=−sin α sin γ +cos α cos β cos γ, F=−sin β cos γ, G=sin α sin β, H=cos α sin β, I=cos β).
5. The method of claim 1 , further comprising, with respect to different angle parameters, repeatedly performing the generating of a second frequency coefficient matrix by performing a partial exchange of one or more values between at least two rows or between at least two columns of the first frequency coefficient matrix, the quantizing of the second frequency coefficient matrix, and the entropy-encoding of the second frequency coefficient matrix; and selecting an angle parameter from among the different angle parameters corresponding to a highest compression rate.
The image encoding method where a "second frequency coefficient matrix" is created by partially exchanging values between rows or columns of the first matrix based on an angle parameter, also includes an optimization process. The method repeatedly generates, quantizes, and entropy-encodes the "second frequency coefficient matrix" using *different* "angle parameters". After each iteration, it selects the "angle parameter" that results in the highest compression rate. This allows the encoder to find the best angle for efficient compression.
6. The method of claim 5 , wherein the selecting of the angle parameter from among the different angle parameters comprises: with respect to the different angle parameters and by using a Monte Carlo method, repeatedly performing the generating of the second frequency coefficient matrix by performing the partial exchange of the one or more values between the at least two rows or between the at least two columns of the first frequency coefficient matrix, the quantizing of the second frequency coefficient matrix, and the entropy-encoding of the second frequency coefficient matrix; and selecting the angle parameter from among the different angle parameters corresponding to the highest compression rate.
The image encoding method where it repeatedly generates, quantizes, and entropy-encodes the "second frequency coefficient matrix" using different "angle parameters" and selects the angle parameter that results in the highest compression rate, further specifies how to optimize the "angle parameter" selection. It utilizes a Monte Carlo method to repeatedly generate, quantize, and entropy-encode using different "angle parameters" in the exchange of row and column values. The angle parameter corresponding to the best compression is selected.
7. The method of claim 5 , wherein the selecting of the angle parameter comprises: corresponding the different angle parameters to a random sequence; and with respect to the different angle parameters, repeatedly performing the generating of the second frequency coefficient matrix by performing the partial exchange of the one or more values between the at least two rows or between the at least two columns of the first frequency coefficient matrix, the quantizing of the second frequency coefficient matrix, and the entropy-encoding of the second frequency coefficient matrix; and selecting the angle parameter from among the different angle parameters corresponding to the highest compression rate, and wherein the entropy-encoding of the information regarding the angle parameter comprises: encoding a number of the random sequence corresponding to the selected angle parameter, as the information regarding the angle parameter.
The image encoding method where it repeatedly generates, quantizes, and entropy-encodes the "second frequency coefficient matrix" using different "angle parameters" and selects the angle parameter that results in the highest compression rate, specifies how the angle parameter is chosen and encoded. It associates the different angle parameters with a random sequence. Then, it repeatedly encodes with different angle parameters, selects the best one, and then encodes the *number* of the selected parameter *within the random sequence* as the "angle parameter" information.
8. The method of claim 7 , wherein the random sequence is Lehmer's pseudo-random numbers.
The image encoding method where the number of the selected parameter *within the random sequence* is encoded as the "angle parameter" information, specifies that the random sequence used is a Lehmer pseudo-random number sequence.
9. The method of claim 1 , wherein the generating of the second frequency coefficient matrix comprises: selecting a matrix comprising only some of coefficients of the first frequency coefficient matrix; and generating the second frequency coefficient matrix by performing a partial exchange of one or more values between at least two rows or between at least two columns of the matrix comprising the selected coefficients, based on an angle parameter.
The image encoding method where a "second frequency coefficient matrix" is created by partially exchanging values between rows or columns of the first matrix based on an angle parameter, pre-selects a subset of coefficients from the "first frequency coefficient matrix". It selects a smaller matrix comprised of only some coefficients of the "first frequency coefficient matrix," and performs the partial exchange operation on this smaller matrix. The "second frequency coefficient matrix" is then generated from this selected matrix.
10. The method of claim 9 , wherein the selected coefficients correspond to a low frequency component from among the coefficients of the first frequency coefficient matrix.
The image encoding method where a "second frequency coefficient matrix" is created by partially exchanging values between rows or columns of the first matrix based on an angle parameter, from a pre-selected subset of coefficients from the "first frequency coefficient matrix," specifies that the selected coefficients correspond to the low-frequency components of the original matrix.
11. An image encoding apparatus comprising: a transformer that generates a first frequency coefficient matrix and generates a second frequency coefficient matrix by performing a partial exchange of one or more values between at least two rows or between at least two columns of the first frequency coefficient matrix based on an angle parameter; a quantization unit that quantizes the second frequency coefficient matrix; and an entropy encoder that entropy-encodes the second frequency coefficient matrix and information regarding the angle parameter, wherein the angle parameter is a parameter that indicates a level of the partial exchange of the one or more values between the at least two rows or between the at least two columns of the first frequency coefficient matrix.
An image encoding apparatus includes a "transformer," a "quantization unit," and an "entropy encoder." The transformer generates a "first frequency coefficient matrix" and then generates a "second frequency coefficient matrix" by performing a partial exchange of values between rows or columns of the first matrix based on an "angle parameter". The "quantization unit" quantizes the second matrix, and the "entropy encoder" entropy-encodes the quantized matrix and information about the "angle parameter".
12. A method of decoding an image, the method comprising: entropy-decoding a second frequency coefficient matrix and information regarding an angle parameter; inverse-quantizing the second frequency coefficient matrix; generating a first frequency coefficient matrix by performing a partial exchange of one or more values between at least two rows or between at least two columns of the second frequency coefficient matrix based on the angle parameter; and inverse-transforming the first frequency coefficient matrix to a pixel domain, and reconstructing a predetermined block, wherein the angle parameter is a parameter that indicates a level of the partial exchange of the one or more values between the at least two rows or between the at least two columns of the second frequency coefficient matrix.
A method for decoding an image involves entropy-decoding a "second frequency coefficient matrix" and the "angle parameter" information. It then inverse-quantizes the decoded matrix. A "first frequency coefficient matrix" is then generated by performing a partial exchange of values between rows or columns of the second matrix, using the "angle parameter". Finally, the first matrix is inverse-transformed back to the pixel domain, reconstructing the original block of the image. The "angle parameter" determines the level of exchange of values.
13. The method of claim 12 , wherein the angle parameter is a parameter with respect to an Euler angle.
The image decoding method where a "first frequency coefficient matrix" is generated by performing a partial exchange of values between rows or columns of the second matrix based on the "angle parameter", specifies that the "angle parameter" is related to an Euler angle, suggesting the transformation involves a rotation-based exchange of values in the frequency domain.
14. The method of claim 12 , wherein the generating of the first frequency coefficient matrix comprises multiplying a matrix for performing the partial exchange between the at least two rows of the second frequency coefficient matrix by a left side of the second frequency coefficient matrix, and multiplying a matrix for performing the partial exchange between the at least two columns of the second frequency coefficient matrix by a right side of the second frequency coefficient matrix.
The image decoding method where a "first frequency coefficient matrix" is generated by performing a partial exchange of values between rows or columns of the second matrix based on the "angle parameter", performs the exchange using matrix multiplication. Specifically, it multiplies a row-exchange matrix on the left side of the "second frequency coefficient matrix," and a column-exchange matrix on the right side.
15. The method of claim 12 , wherein the information regarding the angle parameter is a number of a random sequence corresponding to the angle parameter.
The image decoding method where a "first frequency coefficient matrix" is generated by performing a partial exchange of values between rows or columns of the second matrix based on the "angle parameter", retrieves the "angle parameter" information as a number representing the index of the angle parameter within a pre-defined random sequence.
16. The method of claim 15 , wherein the random sequence is Lehmer's pseudo-random numbers.
The image decoding method that retrieves the "angle parameter" information as a number representing the index of the angle parameter within a pre-defined random sequence, specifies that the random sequence used is Lehmer's pseudo-random number sequence.
17. An image decoding apparatus comprising: an entropy decoder that entropy-decodes a second frequency coefficient matrix and information regarding an angle parameter; an inverse-quantization unit that inverse-quantizes the second frequency coefficient matrix; an inverse-transformer that generates a first frequency coefficient matrix by performing a partial exchange of one or more values between at least two rows or between at least two columns of the second frequency coefficient matrix based on the angle parameter; and inverse-transforms the first frequency coefficient matrix to a pixel domain, and reconstructs a predetermined block, wherein the angle parameter is a parameter that indicates a level of the partial exchange of the one or more values between the at least two rows or between the at least two columns of the second frequency coefficient matrix.
An image decoding apparatus includes an "entropy decoder," an "inverse-quantization unit," and an "inverse-transformer." The entropy decoder decodes a "second frequency coefficient matrix" and the "angle parameter" information. The inverse-quantization unit inverse-quantizes the second matrix. The inverse-transformer generates a "first frequency coefficient matrix" by performing a partial exchange of values between rows/columns of the second matrix based on the "angle parameter". It also inverse-transforms the first matrix to the pixel domain to reconstruct the image block.
18. A non-transitory computer readable recording medium having recorded thereon a program that when executed by a computer performs a method of encoding an image, the method comprising: generating a first frequency coefficient matrix; generating a second frequency coefficient matrix by performing a partial exchange of one or more values between at least two rows or between at least two columns of the first frequency coefficient matrix based on an angle parameter; quantizing the second frequency coefficient matrix; and entropy-encoding the second frequency coefficient matrix and information regarding the angle parameter, wherein the angle parameter is a parameter that indicates a level of the partial exchange of the one or more values between the at least two rows or between the at least two columns of the first frequency coefficient matrix.
A non-transitory computer-readable medium stores a program that, when executed, encodes an image by: generating a "first frequency coefficient matrix"; generating a "second frequency coefficient matrix" by partially exchanging values between rows/columns of the first matrix based on an "angle parameter"; quantizing the second matrix; and entropy-encoding the second matrix and "angle parameter" information.
19. A non-transitory computer readable recording medium having recorded thereon a program that when executed by a computer performs a method of decoding an image, the method comprising: entropy-decoding a second frequency coefficient matrix and information regarding an angle parameter; inverse-quantizing the second frequency coefficient matrix; generating a first frequency coefficient matrix by performing a partial exchange of one or more values between at least two rows or between at least two columns of the second frequency coefficient matrix based on the angle parameter; and inverse-transforming the first frequency coefficient matrix to a pixel domain, and reconstructing a predetermined block, wherein the angle parameter is a parameter that indicates a level of the partial exchange of the one or more values between the at least two rows or between the at least two columns of the second frequency coefficient matrix.
A non-transitory computer-readable medium stores a program that, when executed, decodes an image by: entropy-decoding a "second frequency coefficient matrix" and "angle parameter" information; inverse-quantizing the second matrix; generating a "first frequency coefficient matrix" by partially exchanging values between rows/columns of the second matrix based on the "angle parameter"; and inverse-transforming the first matrix to the pixel domain to reconstruct an image block.
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August 13, 2010
September 10, 2013
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